Air system for sterile areas



Dec. 7, 1965 R. H. coPP AIB SYSTEM FOR STERILE AREAS 2 Sheets-Sheet 1 Filed Jan. 13, 1964 r\/"" ""'INVENTOR Q @MA/ /x da?? BYJQU,%

Dec. 7, 1965 R. H. coPP 3,221,632

AIR SYSTEM FOR S'TERILE AREAS Filed Jan. l5, 1964 2 Sheets-Sheet 2 Fis. 3.

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United States Patent() 3,221,632 AIR SYSTEM FOR STERILE AREAS Roland H. Copp, Grand Rapids, Mich., assigner to Sterilab, Inc., Grand Rapids, Mich., a corporation of Michigan Filed Jan. 13, 1964, Ser. No. 337,335 4 Claims. (Cl. 98-33) This invention relates to sterile enclosures and more particularly to a means of limiting the entrance of noniltered or unsterile air into the enclosure when the access door thereto is opened.

It is particularly desirable in many circumstances to have a reasonably small enclosure in which work can be done in a sterile or reasonably sterile environment. This is particularly true in pharmacies where such an area is desirable for the compounding of prescriptions. Such enclosures have been developed which have proven to be quite satisfactory except that considerable quantities of unfiltered, unclean air enter the enclosure Whenever the door is opened as the pharmacist enters and leaves the enclosure. It is impractical under normal circumstances to provide a subsidiary chamber in the nature of an air lock wherein the pharmacist can enter and then have the non-sterile ambient air removed and replaced by sterile air before he moves on into the sterile enclosure. Such an arrangement would not only be excessively expensive, but would entail substantial time loss on the part of the pharmacist and, therefore, is impractical.

This invention overcomes this problem, providing a simple, inexpensive means by which all or substantially all of the unsterile air which normally enters through the door when it is opened is prevented from entering. Thus, it materially increases the sterility of the interior of the enclosure. It does this automatically, and accordingly, is not subject to failure arising from the normal human tendency of forgetfulness. It executes its purpose by equipment which is simple, dependable and inexpensive. Further, it can be added t-o existing enclosures of this type without diicult modification of the enclosure.

These and other objects and purposes of this invention will be immediately understood by those acquainted with equipment of this type upon reading the following specification and the accompanying drawings.

In the drawings:

FIG. l is a sectional elevation view of a sterile enclosure equipped with this invention illustrating its operation when the door is closed, the air exhaust system being partially broken-out for purposes of illustration;

FIG. 2 is a sectional elevation view of this inventionl illustrating the operation of the invention when the door is open, the air exhaust system being partially broken-out for 'purposes of illustration;

FIG. 3 is a sectional view looking toward the ceiling of the enclosure taken along the plane III-III of FIG. l;

FIG. 4 is a fragmentary, partially broken, enlarged, side elevation View of the invention showing the invention in its normal position in solid lines and in activated position in broken lines;

FIG. 5 is a fragmentary sectional elevation view taken along the plane V-V of FIG. 4;

FIG. 6 is a fragmentary, partially broken, sectional elevation view of a modified form of this invention;

FIG. 7 is a wiring diagram for the invention as illustrated in FIGS. 1 through 5; and c FIG. 8 is a wiring diagram for the invention as illustrated in FIG. 6.

In executing the purposes of this invention a sterile enclosure is provided having a filtered air inlet in one Wall and an exhaust fan in the ceiling. The exhaust fan discharges into a duct having a pair of exhaust ports.

3,221,632 Patented Dec. 7, 1965 ICC One of these ports discharges into the ambient atmosphere externally of the enclosure, and the other port discharges back into the enclosure. A control vane of damper is placed in the duct which is pivotable from a normal position in which it directs the exhaust air to the externally discharging port to a position in which it directs the air to the re-entry or internally discharging port. The device normally discharges the air externally, but when the door of the enclosure is opened, the air is immediately redirected to discharge internally of the enclosure and thus form an air lm in front of the open door.

Referring to the drawings and specifically to FIG. 3, the numeral 10 indicates an enclosure having a back Wall 11, a front wall 12 and a pair of side walls 13. These are closed at the top by a ceiling 14 and at the bottom by a floor 15 (FIGS. l and 2). The front wall 12 has an opening 16 (FIG. 2) normally closed by a door 17. The door may be hung in any suitable manner such as by the hinges 17a and secured in closed position by a latch 17b, the handle of which is illustrated.

The back wall has an air inlet port 18 covered by a suitable filter 19 to prevent the entry of contaminating materials with the air being drawn into the enclosure. The air inlet port 18 need not necessarily be located in the rear wall 11 and `could as Well be located in either of the side Walls 13. The inlet port 18 is the only air source for the interior of the enclosure 10 when the door 17 is closed.

The ceiling 14 of the enclosure is equipped with an air outlet opening 30 through which air passes into a housing 31 containing a power driven exhaust fan 32. The fan forceably draws air from the interior of the enclosure and discharges it through a duct 33.

The end of the duct 33 opposite from the fan 32 is Y- shaped having one portion extending upwardly and another portion extending downwardly. The upwardly extending portion forms an external exhaust port 34 through which air propelled through the duct by the fan will be discharged into the atmosphere externally of the enclosure 10. The other portion of the duct extends downwardly and discharges back into the enclosure through an internal discharge port 35 extending through the ceiling 14 of the enclosure. It will be seen from FIG. 3 that the internal discharge port 35 is located in the ceiling adjacent the door 17 and is elongated parallel to the door to form a long, narrow slot substantially the full width of the door. Further, it will be noted from FIG. 4 that the internal discharge port 35 is inclined at an angle toward the door whereby air discharged from this port will have a tendency to move toward the door rather than back into the inner portion of the enclosure. The shape of the port 35, its location and inclination is such that unless it is operating, it forms an air curtain just inside the door.

Where the two legs of the duct join the main duct 33, a vane or plate is mounted inside the duct on a pivotal bar 41. The plate 40 is pivotally movable from a normal position (illustrated in solid lines in FIG. 4) in which it closes the internal discharge port 35 and opens the external exhaust port 34 to a second position (illustrated in broken lines in FIG. 4) in which it closes the external exhaust port 34 and opens the internal discharge port V35. To do this, a link member 42 is mounted on one end of the bar 41. The end of the link member 42 is connected to a second link member 43 which in turn is connected to the solenoid 44. At the hinge point between the link members 42 and 43, they are connected to a tension spring 45. The other end of the spring 45 is secured to the ceiling 14 and biases the plate 40 into its normal position as illustrated in solid lines in FIG. 4 in which it closes the internal discharge port 35.

Mounted in the wall of the door opening 16 is a switch (FIG. 2). When the door is closed, the plunger 51 of the switch is depressed, opening the switch. When the door is opened, the plunger automatically shifts outwardly closing the switch. The switch is connected electrically to the solenoid 44, as shown in FIG. 7. When the switch 50 is open, the solenoid is deactivated and the spring 45 takes over, biasing the plate 40 into its normal position where it closes the internal port 35. When, however, the door is opened, the switch closes, activating the solenoid 44 overcoming the bias of the spring 45. This pivots the plate 40 to close the external exhaust port 34 and opens the internal discharge port 35 (as illustrated in broken lines in FIG. 4).

It will be seen from FIG. l as indicated by the arrows A and'B that when the door is closed, the fan 32 causes a negative pressure within the enclosure which induces air to fiow through the inlet port 18 and the filter 19 into the enclosure. The air being drawn off from the enclosure is exhausted through the external discharge port 34. When the door is opened and the plate 40 shifts position, air continues to be drawn in through the opening 1S and the filter 19 is indicated by the arrows A in FIG. 2, but this air is then returned to the enclosure as a downwardly discharging film just inside the door opening as indicated by the arrows C. As indicated by the arrows C, this film extends all the way down the door opening and impinges against the floor. The air being discharged as a steady stream just inside the door opening will tend to prevent the entrance of unfiltered and unsterile air through the door. It will have the tendency to push external air out through the door and will even create a certain degree of Venturi action which will also help to cause more air to flow into the enclosure through the filter 19. This air film will exhaust at the bottom of the door opening thus creating an air curtain across the entire door opening. This condition will continue until the door is closed at which time the direction of exhaust automatically will be shifted to that illustrated in FIG. 1. It will be understood that the fan 32 is operated continuously and is not shut ofi, irrespective of whether the door is open or closed.

FG. 6 illustrates a modification of this invention. In this arrangement all of the stucture illustrated in FIGS. l, 2 and 3 is retained. However, an auxiliary air supply duct Si) is provided. This auxiliary duct obtains air externally of the enclosure through a filter 51, thus providing clean, filtered air. The auxiliary duct 5) has a closure damper 52 operated by a solenoid 53 wired in parallel with the solenoid 44. A spring 54 biases the damper 52 to a normally closed position (illustrated in broken lines in FIG. 6) when the solenoid 53 is deactivated.

The damper 52 by means of links S5 is connected to a plurality of shut-off vanes 56 which together with the damper 52, when the damper 52 is open (illustrated in solid lines in FIG. 6) close the air outlet opening 30 in the ceiling of the enclosure. When the damper 52 is erected or closed, it closes the auxiliary duct and the vanes 56 being erected open the air inlet opening 30. Thus, the auxiliary duct 50 is prevented from supplying air to the exhaust fan, forcing the fan to obtain its air from the interior of the enclosure. This is the condition when the door 17 is closed.

However, when the door 17 is opened, the solenoid 53 is activated simultaneously with solenoid 44, opening the damper 52 and shifting the vanes 56 to close the air inlet opening 30. This gives the fan a source of clean filtered air to form the air curtain. However, since the air for this curtain is not obtained from the interior of the enclosure, the fans discharge not only forms an air curtain but builds up a positive pressure within the enclosure. These two forces reinforce each other in preventing the entry of unfiltered, contaminated air through the open door.

It will be seen that this invention provides a simple yet positive means of preventing the entrance of unfiltered and contaminated air into the enclosure despite the fact that personnel have to open the door to enter and leave the enclosure. The air film created by this invention forms a positive barrier which not only seals off the entrance of contaminated air through the open door but tends to push any such air which might attempt to enter outwardly through the door, utilizing the ltered sterile air on the inside of the enclosure as the excluding medium.

While there has been described a preferred embodiment of this invention together with a modification of this embodiment, it will be understood that other embodiments may be made without departing from the spirit of the invention. Such of these embodiments as incorporate the principles of the invention are to be considered as included in the hereinafter appended claims unless these claims by their language expressly state otherwise.

I claim:

1. In an enclosure designed to maintain a sterile internal condition, the combination comprising: a door in one wall of the enclosure; an air inlet for the enclosure mounted through another wall of the enclosure, said air inlet having air cleaning means; a power driven air exhaust fan mounted in a third wall of the enclosure and communicating with the interior of the enclosure to receive air therefrom; said air exhaust fan having a discharge duct; said duct having both a first port discharging externally of said enclosure and a second -port discharging internally of said enclosure; means for directing air from said air exhaust fan alternately to one of said discharge ports, said directing means normally directing air to said first port when said door is closed; control means operated by said door and connected to said directing means and positioning said directing means to direct air to said second port when said door is open to reduce the movement of air into said enclosure through the door opening when said door is open; said second port being a narrow slot adjacent one end of said door and extending substantially the width of said door.

2. An enclosure as described in claim 1 wherein said second port is inclined at a minor angle toward said door to form an outwardly inclined air film directed toward said door opening.

3. In an enclosure designed to maintain a sterile internal condition, the combination comprising: a door in one wall of the enclosure; an air inlet `for the enclosure mounted through another wall of the enclosure, said air inlet having air cleaning means; a power driven air exhaust fan mounted in a third wall of the enclosure and communicating with the interior of the enclosure to receive air therefrom; said exhaust fan having a first air intake opening through a third wall of the enclosure to receive air from the interior of the enclosure and a second air intake open to the exterior of the enclosure, said second air intake having air cleaning means; said air exhaust fan having a discharge duct; said duct having both a first port discharging externally of the enclosure and a second port discharging internally of the enclosure; first directing means for directing air from said air exhaust fan alternately to one of said discharge ports, said first directing means normally directing air to said first port when said door is closed; second directing means for closing and opening said second air intake, said second directing means normally closing said second air intake when said door is closed; control means operated by said door and connected to both said first and second directing means and positioning said first directing means to direct air to said second port and positioning said second directing means to open said second air intake when said door is open to reduce the movement of air into said enclosure through the door opening when said door is open; said second port being positioned in said enclosure to direct air as a film adjacent and in a manner similar to a film across the opening for said door; a

third air directing means; said third directing means being mounted in said first air intake opening and normally opening said first air intake opening for the passage of air therethrough; said third directing means being connected to said second connecting means for simultaneous operation therewith; said second directing means upon opening said second air intake shifting said third directing means to close said first air intake.

4. An enclosure as described in claim 3 having a ceiling and a floor an-d wherein said first air inta-ke and said second port are both in said ceiling; said second port being a narrow slot elongated in the direction 0f the width of said door and extending substantially the width of said door; said second port being inclined at a minor angle toward said door to form an outwardly inclined air lm directed toward said door opening and impinging against said floor at the bottom of said door opening.

References Cited by the Examiner UNITED STATES PATENTS 2,763,195 9/1956 Caldwell 98-36 X 10 3,038,400 6/-19'62 Ruff 98-36 3,089,403 5/1963 Banko 98-36 ROBERT A. OLEARY, Primary Examiner. 

1. IN AN ENCLOSURE DESIGNED TO MAINTAIN A STERILE INTERNAL CONDITION, THE COMBINATION COMPRISING: A DOOR IN ONE WALL OF THE ENCLOSURE; AN AIR INLET FOR THE ENCLOSURE MOUNTED THROUGH ANOTHER WALL OF THE ENCLOSURE, SAID AIR INLET HAVING AIR CLEANING MEANS; A POWER DRIVEN AIR EXHAUST FAN MOUNTED IN A THIRD WALL OF THE ENCLOSURE AND COMMUNICATING WITH THE INTERIOR OF THE ENCLOSURE TO RECEIVE AIR THEREFROM; SAID AIR EXHAUST FAN HAVING A DISCHARGE DUCT; SAID DUCT HAVING BOTH A FIRST PORT DISCHARGING EXTERNALLY OF SAID ENCLOSURE AND A SECOND PORT DISCHARGING INTERNALLY OF SAID ENCLOSURE; MEANS FOR DIRECTING AIR FROM SAID AIR EXHAUST FAN ALTERNATELY TO ONE OF SAID DISCHARGE PORTS, AND DIRECTING MEANS NORMALLY DIRECTING AIR TO SAID FIRST PORT WHEN SAID DOOR IS CLOSED; CONTROL MEANS OPERATED BY SAID DOOR AND CONNECTED TO SAID DIRECTING MEANS AND POSITIONING SAID DIRECTING MEANS TO DIRECT AIR TO SAID SECOND PORT WHEN SAID DOOR IS OPEN TO REDUCE THE MOVEMENT OF AIR INTO SAID ENCLOSURE THROUGH THE DOOR OPENING WHEN SAID DOOR IS OPEN; SAID SECOND PORT BEING A NARROW SLOT ADJACENT ONE END OF SAID DOOR AND EXTENDING SUBSTANTIALLY THE WIDTH OF SAID DOOR. 